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This study examined the impact of adding hard ferrite Ba0.5Sr0.5Fe12O19 (BSF) nanoparticles to the Bi1.8Pb0.4Sr2Ca2Cu3.2O10+δ (Bi, Pb)-2223) superconductor phase. The investigation specifically focused on evaluating the critical current density, fluctuation-induced conductivity, and magnetoresistance of nano-(BSF)x/(Bi, Pb)-2223 composite, where 0.00 ≤ x ≤ 0.20 wt.%. The results revealed that the critical current density, Jc, increased with the addition of nano-(BSF) up to x = 0.04 wt.%, reaching a value of 441.20 A/cm2. The Aslamazov and Larkin (A–L) approach has been evaluated the fluctuation-induced conductivity. Several superconducting parameters, including coherence length ζc(0), effective layer thickness d, penetration depth λpd(0), and Fermi energy E F showed improvement as the concentration of nano-(BSF) increased up to x = 0.04 wt.%. In addition to Ginzburg–Landau critical parameters, such as the thermodynamic critical field Bc(0), lower critical magnetic field Bc1(0), upper critical magnetic field Bc2(0), and critical current density Jc(0) demonstrated an increase up to x = 0.04 wt.%, followed by a decrease for higher concentrations. The magnetoresistance measurements were performed at various applied DC magnetic fields, with values ranging from 0.29 to 4.44 kG, and were analyzed using the thermally activated flux creep (TAFC) and Ambegaokar–Halperin (AH) models. The calculated flux pinning energy (U) increased with the addition of nano-(BSF) up to x = 0.04 wt.% and then decreased for x > 0.04 wt.%. Furthermore, the transition width (ΔT), was observed to increase as the applied magnetic field values increased. Moreover, the addition of nano-(BSF) increased the field-independent critical current density, Jc,0(0), up to x = 0.04 wt.%, after which it decreased for higher concentrations. [ABSTRACT FROM AUTHOR]

The effect of samarium and lanthanum fluorides (SmF3 and LaF3) on the structural and superconducting properties of Tl0.8Hg0.2Ba2Ca2−xRxCu3O9-δ-yFy superconducting phase (Tl, Hg)-1223, where R = Sm or La and x = 0.00, 0.025, 0.050, 0.075, and 0.10 was investigated. The solid-state reaction method was used to synthesize the superconducting samples. The phase formation percentages and lattice parameters were calculated using X-ray powder diffraction (XRD). Images taken with a scanning electron microscope (SEM) show that the presence of both Sm and La increases the grain size and inter-grain connectivity up to x=0.025. The successful substitution of Sm and La elements in the crystal structure of (Tl, Hg)-1223 is confirmed by energy-dispersive X-ray (EDX) analysis. The oxidation states of the elements in the prepared samples are revealed by X-ray photoelectron spectroscopy (XPS) spectra. I–V and resistivity measurements were used to investigate the electrical properties of the (Tl, Hg)-1223 system with Sm and La substitutions. The superconducting transition temperature (Tc) and transport critical current density (Jc) have steadily improved up to x = 0.025, above which they dropped significantly. Furthermore, as temperature increased, the temperature dependence of fluctuation conductivity (Δσ), revealed distinct zones. The zero-temperature coherence length (ξc(0)), effective layer thickness of the two-dimensional system (d), interlayer coupling (I), Fermi velocity (vf), and Fermi energy (Ef) were determined. ξc(0) and d decrease until x= 0.025, then increase as x increases. All estimated I values show weak coupling between CuO2 planes and a transition from three-dimensional (3D) to two-dimensional (2D) regions. [ABSTRACT FROM AUTHOR]

The impact of adding the orthoferrite NdFeO3, at the nanoscale, on the (Cu0.5Tl0.5)Ba2Ca2Cu3O10–δ phase formation, microstructure, electrical and mechanical performance was studied. The nano-(NdFeO3)x/(CuTl)-1223 composites, with x = 0.00, 0.25, 0.50, 0.75, 1.00, and 2.00 wt.%, were prepared using the solid-state reaction technique. The X-ray diffraction (XRD) confirmed that supplementing the host (CuTl)-1223 phase with nano-NdFeO3 did not alter the unit cell parameters (a and c) and preserved the tetragonal structure. SEM micrographs suggested that the inclusion of nano-NdFeO3 reduced the number of voids and boosted the inter-grain connections. The energy-dispersive X-ray (EDX) spectra revealed the elemental compositions of the various superconductor composites. The superconducting transition temperature (Tc) and the critical current density (Jc) increased with the inclusion of nano-NdFeO3 up to x = 0.50 wt.%. X-ray photoelectron spectroscopy (XPS) spectra analysis revealed the elemental composition and oxidation state of all elements. The Vickers microhardness (Hv) measurements were analyzed and compared with five different theoretical models. According to Hv measurements, the modified proportional sample resistance (MPSR) model provided the best theoretical analysis of Hv within the plateau limit regions. Moreover, various mechanical parameters were estimated as a function of the inclusion of nano-NdFeO3. The indentation creep test showed that the composite samples with high nanoparticle concentration (x > 0.50 wt.%) have dislocation creep mechanism, while those with x ≤ 0.50 wt.% followed a dislocation climbs creep mechanism. A comparison between NdFeO3 nanoparticles and other magnetic ferrites and nano-magnetic oxides was reported. [ABSTRACT FROM AUTHOR]

In the present work, the magnetoresistance behavior of (TlF)x-substituted (Cu0.5,Tl0.5)Ba2Ca2Cu3O10−δ superconducting samples, with x = 0.0, 0.1, 0.2, 0.3 and 0.4, was investigated. According to the thermally activated flux creep (TAFC) model, the flux pinning energies U(H, T) were calculated from the resistivity temperature (ρ–T) curves at applied DC magnetic fields ranging from 0.29 to 4.44 kOe. The results indicated that flux pinning energy was increased with increasing the F-substituting up to x = 0.1 and then decreased with increasing the applied field up to 4.44 kOe. Moreover, significant resistive broadening (ΔT) was observed with increasing the values of the applied magnetic fields. Furthermore, the (TlF)x substitution, boosting the transport critical current density Jc(0) and irreversibility magnetic field Hirr(0) up to x = 0.1 and then decreasing for x > 0.1 at various applied magnetic fields, demonstrates strong flux pinning for x = 0.1. [ABSTRACT FROM AUTHOR]

The current investigation reports the influence of the addition of CdFeO nanoparticles on the structural and superconducting properties of the (Bi,Pb)-2212 phase. The formation of an orthorhombic phase of Bi-2212 superconductor is confirmed by the X-ray powder diffraction measurements. The scanning electron microscope measurements show an improvement in the grain connectivity and a decline of voids due to the CdFeO nanoparticles addition. The Fourier transform infra-red spectroscopy is used to associate the absorption bands to equivalent functional groups. The DC-electrical resistivity and the I-V characteristic measurements show an enhancement of the superconducting transition temperature (Tc) and the critical current density (Jc) up to 0.02 wt% addition of CdFeO, respectively. The elemental composition and oxidation states are determined using X-ray photoelectron emission spectroscopy. The results suggest a correlation between the electric behavior and the cationic equilibrium reactions among Pb2+ ions in Bi3+ or Cu2+ sites. [ABSTRACT FROM AUTHOR]

The effect of CdMnO addition on the physical properties of Bi-2212 superconductors was investigated. The conventional solid-state reaction technique was employed for the synthesis of (Cd0.95Mn0.05O)x Bi1.6 Pb0.4 Sr1.9 Ca1.1 Cu2.1 O8+δ samples with 0.00 ≤ x ≤ 0.10 wt.%. The X-ray diffraction confirms the formation of the orthorhombic phase of Bi-2212 superconductors. The lattice parameter a shows an increase with x, conversely the lattice parameters b and c show a decrease. The scanning electron microscope (SEM) images have shown an enhancement in the grain connectivity and a reduction of voids due to the CdMnO addition. The Fourier transform infrared (FTIR) spectroscopy analysis shows a remarkable shift in the wave number positions due to the addition of CdMnO nanoparticles. The superconducting transition temperature (Tc) and the critical current density (Jc) show an enhancement with CdMnO addition up to x = 0.05 wt.%. The elemental composition and oxidation state of all elements were determined from the X-ray photoelectron emission (XPS) analysis. The work suggests a correlation between the variations of the superconducting properties and the dynamics of the cationic equilibrium reactions among Pb2+ ions in Bi3+ or Cu2+ sites. These equilibrium reactions are induced by the variations in the oxygen content produced by the addition of CdMnO nanoparticles. [ABSTRACT FROM AUTHOR]

The effect of Arsenic substitution on the properties of Bi-2212 superconductors was studied. Solid-state reaction technique was used for the synthesis of Bi2−xAsxSr2Ca1.1Cu2.1O8 samples, x = 0, 0.1, 0.2 and 0.4. The X-ray diffraction confirmed the formation of the tetragonal phase of Bi-2212 superconductors. The decrement in the c parameter confirmed that As insertions were introduced into the Bi sites of the system. The grain morphology of the surface was analysed by scanning electron microscopy, where the amount of arsenic increases with As substitution. The superconducting transition temperature (Tc) was determined from the DC-electrical resistivity by the standard four-probe technique. Tc was enhanced up to x = 0.1 above which it was suppressed. For magnetism, half magnetic-hysteresis loops were obtained by SQUID magnetometer at different temperatures (5 and 30 K). The hysteresis loops sizes increased with increasing As-concentrations. The critical current density (Jc) and the flux pinning mechanisms were investigated via different models. [ABSTRACT FROM AUTHOR]

In this study, the effects of (K6[(H2O)MnSiW11O39]·21H2O, {MnSiW11}) polyoxometalate, with an average particle size of 48.46 nm, on (Bi1.8Pb0.4)Ca2Sr2Cu3O10+δ (Bi,Pb)-2223, superconducting samples, were investigated. Samples of type {MnSiW11}x(Bi1.8Pb0.4)Ca2Sr2Cu3O10+δ, 0.00 ≤ x ≤ 0.20 (wt%) were prepared using the conventional solid-state reaction technique. Manganese-containing polyoxometalates are considered as an attractive class of inorganic nanomaterials, because they have multiple oxidation states and many unpaired electrons. Consequently, the microstructure, morphology, optical and magnetic properties of the prepared {MnSiW11} nanoparticles were determined by powder X-ray diffraction (XRD), transmission electron microscopy, Fourier transform infrared spectroscopy and magnetic hysteresis loop measurements, respectively. The bulk of superconducting samples was characterised by XRD, scanning electron microscopy and energy dispersive X-ray spectroscopy. The XRD analysis showed that the addition of small amounts of {MnSiW11} nanoparticles improves (Bi,Pb)-2223 phase formation significantly. The lattice parameters (a and c) of (Bi,Pb)-2223 phase did not change with the addition of nanoparticles. Furthermore, the superconducting transition temperature (Tc) was determined from dc electrical resistivity (ρ − T) as a function of temperature measurements. Tc was enhanced as x increased up to x = 0.12 wt%, then decreased gradually with a further increase in the concentration of nanoparticles. The (E − J ) measurements were conducted at 77 K with 1 μV/cm. It showed that the critical current density (Jc) of the samples increased from about 301.9 to 728.4 A/cm2 as x increased from 0.00 to 0.12 wt%. The suppression in Tc and Jc for x > 0.12 wt% samples may be due to the decrease in the volume fraction of a high-Tc (Bi,Pb)-2223 phase and the increase of weak links connectivity among the grain boundaries. [ABSTRACT FROM AUTHOR]

Gd-123 superconducting phase was prepared by solid-state reaction technique. Single-walled carbon nanotubes (SWCNTs) were added in Gd-123 superconducting matrix with different concentrations during the final sintering process to obtain (SWCNTs) GdBa2Cu3O ( x = 0.0-0.1 wt.%) nanoparticles-superconductor composite. The influence of SWCNTs addition on the phase formation, structural, morphological, superconducting and dielectric properties of Gd-123 phase was investigated. It was found that SWCNTs addition enhance the phase formation and does not change the crystal structure of the host Gd-123 superconducting phase. The superconducting properties of Gd-123 samples were improved after the addition of SWCNTs up to x = 0.06 wt.% due to the enhancement in intergrain connectivity by healing up of micro-cracks and reduction of defects, while these properties were retarded with further increase in x. The dielectric response of (SWCNTs) Gd-123 superconducting phase with x = 0.0, 0.01, 0.04, 0.05, 0.06 and 0.1 wt.% was measured from 100 KHz to 5 MHz at 77 K. The results reveal that for both real () and imaginary () parts of dielectric constant, the frequency of dispersion increased by increasing SWCNTs amount up to 0.06 wt.%, then this frequency shifted to lower values for x 0.06 wt.%. The results were discussed according to the presence and interference of both interfacial and dipolar polarizations. [ABSTRACT FROM AUTHOR]

The influence of barium tin oxide nanoparticles addition on the structural and superconducting properties of the $$\hbox {Cu}_{0.5}\hbox {Tl}_{0.5}\hbox {Ba}_{2}\hbox {Ca}_{2}\hbox {Cu}_{3}\hbox {O}_{10{-}\delta }$$ phase, (CuTl)-1223, was studied. A different wt% of $$\hbox {BaSnO}_{3}$$ , ranging from 0.00 to 1.50, were added into (CuTl)-1223 phase, and this composite was synthesized using the solid-state reaction technique. The phase formation and lattice parameters were calculated from X-ray powder diffraction measurements. The grain connectivity and surface morphology were identified using scanning electron microscope. Energy dispersive X-ray spectroscopy gave the real elemental composition of the prepared samples. Superconducting transition temperature $$({T_\mathrm{c}})$$ and critical current density $$({J_\mathrm{c}})$$ were determined from the electrical resistivity and I-V measurements, respectively. A complete study about the vibration modes of different atoms was carried out using Fourier transform infrared (FTIR) absorption spectroscopy of $$(\hbox {BaSnO}_{3})_\mathrm{x}/\hbox {CuTl-1223}$$ composite. The increase in $${T_\mathrm{c}}$$ and $${J_\mathrm{c}}$$ up to $$x=0.25$$ wt% is an evidence for improving the superconducting properties of $$(\hbox {BaSnO}_{3})_\mathrm{x}/\hbox {CuTl-1223}$$ composites by enhancing both the inter-grains coupling and volume fraction of the (CuTl)-1223 phase. [ABSTRACT FROM AUTHOR]

Solid-state reaction method was used to prepare superconductor samples with nominal composition of (SnO)(BiPb)SrCaCuO, (SnO)(Bi,Pb)-2223 composite, where 0.0 ≤ x ≤ 0.2 wt%. The prepared samples were characterized by X-ray diffraction (XRD) as well as scanning electron microscopy (SEM). XRD patterns proved that the addition of nano-SnO particles to (Bi,Pb)-2223 did not affect the tetragonal structure and the lattice parameters of this phase. Vickers microhardness measurements ( H ) for these samples were carried out at room temperature as a function of applied load, heating temperatures, and dwell time. However, to clarify the indentation size effect (ISE) behavior of these composite materials and to estimate the true microhardness values ( H ), different models including Meyer's law, Hays and Kendall (energy dissipation) model, elastic/plastic deformation model, as well as proportional specimen resistance model were applied. Some important mechanical parameters, such as Young's modulus ( E), yield strength ( Y), fracture toughness ( K), and brittleness index ( B), were estimated from the microhardness curves. It was found that the incorporation of a proper concentration of nano-SnO particles has proved their efficiency to enhance the mechanical properties of superconductors. Moreover, it was noted that dwell time and Vickers microhardness were inversely proportional. Indentation creep experiments showed that the operative creep mechanisms in the studied samples were dislocation creep in addition to dislocation interaction. [ABSTRACT FROM AUTHOR]

Cobalt zinc ferrite nanoparticles (CoZnFeO) (∼5-8 nm in size) added to CuTlBaCaCuO superconductor samples, 0.00 ≤ x≤ 0.20 wt. %, were prepared using a singlestep solid-state reaction technique. The temperature dependence of the real ( χ ) and imaginary ( χ ) components of the magnetic susceptibility (ACMS) was measured at various ac magnetic field amplitudes (3-16 Oe). The results were analyzed by using Bean critical state model to estimate the critical current density ( J ) It was found that J increases as x increases up to 0.08 and then it decreases with further increase in x. X- and Q-Band (9.3 and 33. GHz) electron paramagnetic resonance (EPR) spectra were measured in the temperature range from 300 to 10 K.The g values of Cu monomer were found to correspond to that of rhombic site symmetry with g = 2.21 ± 0.02, g = 2.10 ± 0.02, and g = 2.02 ± 0.02. [ABSTRACT FROM AUTHOR]

The corrosion behavior of (SnO2)x(Bi1.6Pb0.4)Sr2Ca2Cu3O10-δ, (SnO2)x(Bi,Pb)-2223, in 0.5 M NaCl solutions at 30°C was studied using potentiodynamic polarization curves measurements, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques as well as scanning electron microscopy (SEM) and energy dispersive X-ray emission spectroscopy (EDX). The polarization data indicated that SnO2nanoparticles behave as a cathodic type inhibitor for the corrosion of (Bi–Pb)-2223 phase superconductors in simulating seawater solutions. The corrosion current density of (SnO2)x(Bi,Pb)-2223 in a NaCl solution decreases with the time elapsed from sample preparation. The CV of (SnO2)x(Bi–Pb)-2223 phase superconductors showed features similar to those of ideal capacitive behavior. The results indicated that a pure (Bi,Pb)-2223 phase superconductor is the most suitable choice for electrochemical capacitor applications in simulating seawater solutions. However, EIS measurements at different potentials revealed that the corrosion process is controlled not only by charge transfer but also by the diffusion process. These measurements also confirm that the corrosion rate of a cathodically polarized phase superconductor is less than that of an anodically polarized phase superconductor. SEM images and EDX analysis showed that the reduction of SnO2nanoparticles to Sn decreases the corrosion rates of the superconducting materials. [ABSTRACT FROM AUTHOR]

Superconducting samples of type substituted by both and ions were prepared by a solid-state reaction technique. These substitutions affect the phase formation, lattice parameters, grains formations and superconducting transition temperature . The change in these parameters is mainly due to the partial substitution of by ions rather than the partial substitution of by ions. The analysis of the electrical resistivity versus temperature above was carried out using Aslamazov-Larkin (AL) and Lawrence-Doniach (LD) models. Different fluctuation regions starting from high temperature up to were estimated, and denoted by short-wave (sw), two-dimensional (2D), three-dimensional (3D) and critical (cr) fluctuations. A distinct crossover temperature from 2D to 3D, in the mean field region (MFR), is shifted to lower temperature by increasing substitutions content. The superconducting parameters such as zero temperature coherence length along the -axis , inter-layer coupling strength , Fermi velocity of the carriers and Fermi energy were calculated as a function of substitution content. [ABSTRACT FROM AUTHOR]

The effect of the partial substitution of Ca by Ho ions on the electrical and mechanical properties of the superconducting phase (Bi,Pb)-2223 was studied. Superconducting samples of the type (BiPb)SrCaHoCuO were prepared by solid-state reaction technique under ambient pressure, and characterized by means of X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The superconducting transition temperature T and pseudogap temperature T* were estimated from electrical resistivity measurements, while the critical current density J was determined from I-V curves. The electrical resistivity data were discussed according to bipolaron model in the absence of thermally excited individual polarons. The sample with x = 0.025 showed the highest phase volume fraction, T, and J. Room temperature Vickers microhardness measurements were carried out at different applied loads (0.25-5 N) in order to investigate the performance of the mechanical properties of (BiPb)SrCaHoCuO phase. It was found that all the samples exhibit normal indentation size effect (ISE). The Vickers microhardness number H increased as x increased from 0 to 0.025. The experimental results were discussed in view of Meyer's law, Hays-Kendall (HK) approach, elastic/plastic deformation (EPD) model, and proportional specimen resistance (PSR) model. The load independent (true) microhardness of (BiPb)SrCaHoCuO superconducting samples showed identical behavior to that of the PSR model. [ABSTRACT FROM AUTHOR]

Superconductor samples of type (CoFeO)xGdBaCuO (0≤ x≤0.1) were synthesized by the conventional solid-state reaction technique, whereas nanosized CoFeO was prepared by co-precipitation method with grain size of about 8.5 nm. The elemental content of the prepared samples was determined using particle induced X-ray emission (PIXE). The temperature dependence of real (χ') and imaginary (χʺ) components of AC magnetic susceptibility (ACMS) at different magnetic field amplitude (3-15 Oe) was investigated. The analysis of the temperature dependence of ACMS was performed using Bean critical state model. The values of the critical current density J at T > T ( T is the inter-granular loss peak temperature) were calculated as a function of magnetic field and nanosized CoFeO content. It was found that the low nanosized CoFeO addition content ( x = 0.01) improves the critical current density J of Gd-123 superconducting phase. The observed variation of J with temperature indicated that the weak links are changed from superconductor-normal metal-superconductor (SNS) for free sample to superconductor-insulator-superconductor (SIS) type of junctions for samples added with nanosized CoFeO of x > 0.01. We also discussed the experimental results in the framework of the critical state model to estimate the effective volume fraction of the grains f using Cole-Cole plots. [ABSTRACT FROM AUTHOR]

Superconductor samples of type (CoFeO)GdBaCuO, 0.0≤ x≤0.1 wt.%, were synthesized by the conventional solid-state reaction technique. The prepared samples were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), electrical resistivity, AC magnetic susceptibility, and Vickers microhardness. Phase examination by XRD indicated that the orthorhombic structure of Gd-123 is not affected by nanosized ferrite CoFeO addition, whereas the volume fraction of Gd-123 increased with x up to 0.01 wt.%. Morphological investigations by SEM revealed that the porosity among grains decreased as x increased from 0.0 to 0.1 wt.%. The superconducting transition temperature T was estimated from electrical resistivity and the AC magnetic susceptibility measurements. A reduction in T was observed as x increased from 0.0 to 0.1 wt.%, consisting with the effect of adding magnetic impurities to HTSCs. Room temperature microhardness measurements were carried out at different applied loads (0.5-10 N) for the study of the mechanical performance of the studied samples. The experimental results were analyzed using Meyer's law, Hays-Kendall approach, elastic/plastic deformation model, and proportional specimen resistance model. The results showed that all the samples exhibited normal indentation size effect, and Vickers microhardness values were increased as nanosized CoFeO addition increased. The analysis showed that the proportional specimen resistance model is the best model for computing the load-independent microhardness values of our samples. [ABSTRACT FROM AUTHOR]

Superconductor samples of type BiPbSrCaCuO added with nano ZnO and FeO were synthesized by the conventional solid-state reaction technique. The samples were characterized using X-ray powder diffraction (XRD), scanning electron microscope (SEM), differential scanning calorimetry (DSC) and electrical resistivity measurements. Excess conductivity analysis of the investigated samples was carried out as a function of temperature using Aslamazov and Larkin (AL) model. The analysis showed four different fluctuation regions namely critical (cr), three-dimensional (3D), two-dimensional (2D) and short-wave (sw). The zero temperature coherence length along c-axis, effective layer thickness of the two-dimensional system and inter-layer coupling strength were estimated as a function of nano-oxides concentration. In addition, the thermodynamics, lower and upper critical magnetic fields as well as critical current density were calculated from the Ginzburg number N. It was found that the low concentration of nano-ZnO addition up to x=0.2 wt.% improved the physical properties of (Bi,Pb)-2223 phase. In contrary, these properties were deteriorated for x>0.2. These results indicated that the addition of a low amount of nano-ZnO during the final processing of (Bi,Pb)-2223 samples can be effectively improved the flux pinning ability, while the addition of a high amount of nano-ZnO decreased the volume fraction and increased the resistance of grain boundaries. Moreover, the addition of nano-FeO had a negative effect on the superconducting parameters of the (Bi,Pb)-2223 phase. This behavior was attributed to the decrease in the volume fraction of (Bi,Pb)-2223 phase with the increasing of nano-FeO. [ABSTRACT FROM AUTHOR]

The effect of different weight percentages of nano-FeO on the properties of BiPbSrCaCuO superconducting phase was studied. Phase formation, elemental real contents and granular microstructure of the investigated samples were carried out using X-Ray powder Diffraction (XRD), Energy Dispersive X-ray emission (EDX), Proton Induced X-ray Emission (PIXE), Rutherford Backscattering Spectrometry (RBS) and Scanning Electron Microscopy (SEM). XRD data indicated that the volume fraction of (Bi,Pb)-2223 decreased as nano-FeO wt.% increased. PIXE and EDX analyses showed that the PIXE technique is more accurate for detecting the nano-FeO than the EDX technique. The oxygen content, determined from RBS, decreased as nano-FeO wt.% increased. The superconducting properties of the prepared samples were investigated using electrical resistivity and I- V curves, at 77 K, measurements. It was found that the granular structure and the critical current density were improved up to 0.2 wt.% of nano-FeO addition. The superconducting transition temperature T decreased as nano-FeO wt.% increased, attributing this to the decrease of the volume fraction or trapping of mobile holes. The enhancement rate of J for (Bi,Pb)-2223 phase added with nano-FeO is 9 %, which is lower than that of (Bi,Pb)-2223 phase added with SnO, AgO, AlO and MgO. This means that the nano-magnetic addition has the lowest enhancement rate in both J and T. [ABSTRACT FROM AUTHOR]

Superconducting samples of type (nano-Ag) xCu 0.5Tl 0.5Ba 2Ca 2Cu 3O 10−δ, x=0.0,0.5,1.0,1.5,2.0, and 3.0 wt.% of the total sample’s mass were prepared by a single step solid-state reaction technique. The prepared samples were characterized using X-ray powder diffraction (XRD) and a scanning electron microscope (SEM). The electrical properties of the prepared samples were investigated using the electrical resistivity and I– V measurements. The Vickers microhardness ( Hv) was measured at different applied loads (0.25–3.0 N) for studying the mechanical performance of the prepared samples. All prepared samples exhibited normal indentation size effect (normal ISE) and the Hv number was load dependent. Hv number increases as nano-Ag addition increased. The experimental data of Hv was analyzed using different models; Mayer’s law, Hays–Kendall (H–K) approach, elastic/plastic deformation (EPD) model, proportional specimen resistance (PSR) model, and indentation induced cracking (IIC) model. In addition, the true microhardness ( Ho) values were evaluated through different models. The obtained data has good agreement with the PSR model. Also, Young’s modulus ( E), yield strength ( Y), fracture toughness ( Kf), and brittle index ( Bi) were calculated. [ABSTRACT FROM AUTHOR]

Superconducting samples of type (CuTl)-1223 added with nano-FeO ( x=0.0, 0.1, 0.2, 0.4, 0.6 and 1.0 wt.%) were prepared by solid-state reaction technique. The prepared samples were characterized using X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) for phase analysis and microstructure examination. The elemental content of the prepared samples was determined using particle induced X-ray emission (PIXE), whereas the Oxygen-content of these samples was obtained using non Rutherford backscattering spectroscopy at 3 MeV proton beam. It was found that the Oxygen-content of (CuTl)-1223 phase was not affected with the addition of nano-FeO. The electrical resistivity measurements showed that the superconducting transition temperature ( T) increases up to x=0.2 wt.%, followed by a systematic decrease for x>0.2 wt.%. In addition, room temperature Vickers microhardness ( H) measurements were carried out at different applied loads (0.49-2.94 N) to study the performance of the mechanical properties of samples. The experimental results of H were analyzed using different models such as elastic, energy dissipation, energy balance and modified energy balance models. It has been found that the energy dissipation model is in a good agreement with the microhardness data. [ABSTRACT FROM AUTHOR]

Superconducting samples of type (CoFeO)GdBaCuO, 0.0≤ x≤0.1 wt.%, have been prepared by the conventional solid-state reaction technique and characterized using X-ray powder diffraction (XRD) and the scanning electron microscope (SEM). XRD analysis indicates that the orthorhombic structure of Gd-123 is not affected by the nanosized ferrite CoFeO addition, whereas the volume fraction of Gd-123 increases with x up to 0.01 wt.%. Nanosized ferrite CoFeO has been prepared by Co-precipitation method with grain size about 8 nm. The temperature dependence of electrical resistivity has been measured in zero and 0.44 T magnetic fields. Magneto-conductivity data has been analyzed in terms of Aslamazov-Larkin (AL) and Maki-Thompson (MT) models for layered superconductors, considering the orbital contribution. The superconducting parameters such as the coherence lengths along ab plane ξ(0) and along c-direction ξ(0) at 0 K, anisotropic parameter Γ and phase breaking time τ at 100 K have been determined as a function of nanosized ferrite CoFeO contents. It is found that the low nanosized CoFeO addition contents up to x=0.01 wt.% improves the physical properties of Gd-123, while for x>0.01 wt.% these properties are deteriorated. [ABSTRACT FROM AUTHOR]

Superconducting samples of type (nano-Ag)CuTlBaCaCuO, x=0.0, 0.5, 1.0, 1.5, 2.0 and 3.0 wt.%, were prepared under ambient pressure via a single step solid-state reaction technique at 850 °C. The prepared samples were characterized by means of X-ray powder diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray (EDX) and differential scanning calorimetry (DSC). The electrical properties of the prepared samples were investigated using the electrical resistivity and I- V measurements. The low addition of nano-Ag up to x=1.5 wt.% enhanced the phase formation and improved the superconducting transition temperature T, critical current density J, and melting temperature. For x>1.5 wt.%, a reverse trend was observed. [ABSTRACT FROM AUTHOR]

In this study, superconducting samples of type CuTlBaCaCuO added by SnO and InO in nano-scale were prepared by a solid-state reaction technique. The concentrations of both SnO and InO were 0.0, 0.1, 0.2, 0.4, 0.6 and 1.0 wt% of the sample's total mass. The prepared samples were characterized using X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) for phase analysis and microstructure examination. The elemental content of the prepared samples was determined using energy dispersive X-ray (EDX) and particle induced X-ray emission (PIXE). The results of elemental content, determined from EDX and PIXE, were compared and discussed. In addition, The oxygen content of these samples was obtained using non Rutherford backscattering spectroscopy (RBS) at 3 MeV proton beam. It was found that the Oxygen-content of (CuTl)-1223 phase was not affected by both SnO and InO nano-oxides addition. The electrical resistivity of the prepared samples was measured by the conventional four-probe technique from room temperature down to the zero superconducting transition temperature ( T). An increase in the superconducting transition temperature T from 106 to 119 K was observed as x was varied from 0.0 to 0.6 wt% for (SnO)CuTlBaCaCuO, followed by a systematic decrease with increasing nano-SnO addition. On the other hand, the T values for (InO)CuTlBaCaCuO show a small variation with x. Moreover, the variation rate of T with x, for both nano-additions, was found to be directly proportional to the variation of the volume fraction of the prepared samples. [ABSTRACT FROM AUTHOR]

The Vickers microhardness of BiPbSrCaCuO superconducting phase with added SnO nano-particles was investigated. The concentration of SnO nano-particles x varied from 0.0 to 2.0 of the sample's total mass. The experimental data of the Vickers microhardness were analyzed using Meyer's law, the elastic/plastic deformation model, Hays-Kendall's approach and the proportional specimen resistance model. The Vickers microhardness number H increased as x increased up to 0.4 wt%. The load dependence of H exhibited a normal indentation-size effect, H increased as the applied load increased. Moreover, this dependence was well fitted with the Hays-Kendall approach rather than the elastic/plastic deformation and proportional specimen resistance models. In addition, we calculated Young modulus, yield strength, fracture toughness and brittleness index as a function of both applied load and SnO nano-particle concentration. [ABSTRACT FROM AUTHOR]

Bulk superconducting samples of type TlPbSrBaCaCuRuO, (Tl,Pb)/Sr-1212, with 0.0≤ x≤0.525 were synthesized by the conventional one-step solid-state reaction technique via a short time, using SrO instead of SrCO. X-ray powder diffraction XRD, scanning electron microscope SEM and the electrical resistivity measurements at different applied dc magnetic fields (0.0-4.4 kG) were performed in order to investigate the effect of Ru ions substitution on (Tl,Pb)/Sr-1212 phase. Enhancement of the phase formation, the superconducting transition temperature T and the hole carriers concentration P was observed up to x=0.075, and they decreased for further increase in x. The magnetoresistance data of these samples were analyzed within the thermally activated flux creep TAFC model and the Ambegaokar and Halperin AH theory. The derived flux pinning energy U, the critical current density J(0) and the upper critical magnetic field B(0) enhanced up to x=0.075, beyond which they decreased for further increase in Ru-content. The coherence length at 0 K ζ(0) decreased up to x=0.075 and increased with x>0.075. In addition, we reported a comparison between the effect of Ru substitution on the physical properties for Gd-123, (Bi,Pb)-2223 and (Tl,Pb)/Sr-1212 phases. [ABSTRACT FROM AUTHOR]

In this study, superconducting samples of type CuTlBaCaCuO,(CuTl)-1223, added by SnO and InO in nano-scale were prepared by a solid-state reaction technique. The concentrations of both SnO and InO were varied from 0.0 to 1.0 wt.% of the total sample's mass. The prepared samples were characterized using X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) for phase analysis and microstructure examination, respectively. The electrical resistivity of the prepared samples was measured by the conventional four-probe technique from room temperature down to the zero superconducting transition temperature ( T). An increase in T is observed up to x=0.6 wt.% for (SnO) CuTlBaCaCuO, followed by a systematic decrease with increasing nano-SnO addition for x>0.6 wt.%. While, for (InO) CuTlBaCaCuO the T is slightly changed with x. Room temperature Vickers microhardness measurements were carried out at different applied loads (0.49-2.94 N) for the study of the mechanical performance of the prepared samples and examination of the effect of different nano-oxides addition on the microhardness of (CuTl)-1223 phase. Furthermore, the true microhardness values ( H), for both additions, were evaluated through different models and their results were compared with those estimated from the experimental results in the plateau region. Also, some important mechanical parameters, such as Young's modulus ( E), yield strength ( Y), fracture toughness ( K) and brittleness index ( B), were calculated for both additions. The results clarified that these parameters are strongly dependent on both the applied loads and the nano-oxides addition. [ABSTRACT FROM AUTHOR]

Series of superconducting samples of type CuTl BaCaRCuO, where R=Pr and La with 0≤ y≤0.20, were prepared in a sealed quartz tube via a single-step solid-state reaction technique. The prepared samples were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), and electron dispersive X-ray (EDX). XRD studies indicated that the tetragonal structure of (CuTl)-1223 phase does not change by Pr or La-substitutions whereas the lattice parameters a and c do. The elemental compositions analysis, determined from EDX, indicated that both Pr and La were successfully introduced into the microstructure of (CuTl)-1223 phase. The electrical resistivity ρ( T) was measured as a function of temperature using conventional dc four-probe technique. The fluctuation conductivity Δ σ, above the superconducting transition temperature T, was analyzed as a function of temperature using Aslamazov and Larkin model. It exhibits four different fluctuation regions namely critical (cr), three-dimensional (3D), two-dimensional (2D), and short-wave (sw). The zero-temperature coherence length, effective layer thickness of the two-dimensional system and inter-layer coupling strength were estimated as a function of the substitution-content y. Furthermore, the thermodynamics critical field, lower critical magnetic field, upper critical magnetic field, critical current density and Fermi energy were calculated from the Ginzburg number. The data indicated that both Pr and La-substitutions have quite similar behaviors. [ABSTRACT FROM AUTHOR]

Systematic studies on the TlAsBaCaCuO system, with 0.0≤ x≤0.3, were carried out to investigate the effect of arsenic on the superconductivity of Tl-1223 phase. The prepared samples were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), electron dispersive X-ray (EDX) and electrical resistivity measurements. XRD studies indicated that the tetragonal structure of Tl-1223 phase does not change by arsenic substitution whereas the lattice parameters a and c do. The elemental compositions analysis, determined from EDX, indicated that the arsenic was successfully introduced into the microstructure of Tl-1223 phase. The superconducting transition temperature T, determined from electrical resistivity data, increased from 122 to 127 K as x increased from 0.0 to 0.025 and then it suppressed with further increase in x. This means that the lower As-content may stabilize the Tl-1223 phase. In order to study the effect of arsenic substitution on the thermodynamic fluctuations of the Cooper pairs, above T, the excess conductivity analysis were performed using Aslamazov-Larkin (AL) theory. The results clarified that there are four regions appeared as the temperature increases namely critical (cr), three-dimensional (3D), two-dimensional (2D), and short-wave (sw) fluctuations. The zero-temperature coherence length along c-axis, the effective layer thickness of the two dimensional system, and the interlayer coupling strength were estimated as a function of the As-content. Furthermore, the thermodynamics critical field, lower critical magnetic field, upper critical magnetic field, critical current density, and Fermi energy were calculated from the above measurements. [ABSTRACT FROM AUTHOR]

Superconducting samples of type TlBa2Ca3− yEr yCu4O11− δ and Cu0.25Tl0.75Ba2Ca3− yEr yCu4O12− δ, y ranging from 0.0 to 0.1, have been prepared by a single step of solid-state reaction technique at normal pressure using high-purity oxide elements. The lattice parameters, for prepared samples, have been estimated from X-ray powder diffraction (XRD). The elemental stoichiometry of the prepared samples has been determined using Particle Induced X-ray Emission (PIXE), whereas the oxygen-content has been determined using elastic backscattering spectroscopy at 3 MeV proton beam. The superconducting transition temperature T c has been determined from the electrical resistivity measurements. The data of T c, for TlBa2Ca3− yEr yCu4O11− δ, show enhancement in its value from 124.5 to 128.45 K as y (Er-content) increases from 0.0 to 0.05, whereas it began to suppress with further increase in y. T c gradually suppresses with increase of yfor Cu0.25Tl0.75Ba2Ca3− yEr yCu4O12− δ. Finally, the applied magnetic field B=0.44 T shows enlargement in the transition width. The effect of magnetic field on Tl-1234 phase is a little higher than that on (Cu0.25Tl0.75)-1234, indicating that the anisotropy parameter Γ for Tl-1234 is slightly higher than that for (Cu0.25Tl0.75)-1234. [ABSTRACT FROM AUTHOR]

Abstract: Bulk Tl0.8Hg0.2Ba2Ca2−x Sm x Cu3O9−δ superconducting samples with x =0.00, 0.025, 0.05, 0.10, 0.15, and 0.20 were prepared, in a sealed quartz tube, by a single step solid-state reaction technique. The prepared samples were investigated using X-ray powder diffraction, scanning electron microscope, electron dispersive X-ray, electrical resistivity, ac magnetic susceptibility and electron paramagnetic resonance. Powder X-ray diffraction analysis revealed that the prepared samples are nearly single phase of (Tl, Hg)-1223 with tetragonal structure (space group P/4mmm). The temperature dependence of the electrical resistivity and the ac magnetic susceptibility was investigated to study the effect of Sm-substitution, on the superconducting transition temperature T c and the intergrain critical current density J c. The data showed a T c suppress as Sm-content increases, whereas J c increases up to x =0.05, after that it depresses with further increase in x. Furthermore, electron paramagnetic resonance (EPR) spectrum at room temperature was studied for the prepared samples. The values of the gyromagnetic factors, g ⊥, g ∥, the hyperfine structure and the spin density were calculated as a function of Sm-content. [Copyright &y& Elsevier]

Abstract: Cu0.5Tl0.5Ba2Ca2−x Cd x Cu3O10−δ superconductor samples (x =0–0.8) were prepared by a single-step solid-state reaction technique in order to investigate the effect of Cd-substitution on the formation and the transport properties of the (Cu, Tl)-1223 phase. A nearly single-phase materials is synthesized with x =0.2 and found to have optimum superconducting transition temperature T c and critical current density J c. The dielectric constant and the loss tangent, for all the prepared samples, were measured at room temperature as a function of frequency up to 5MHz. The normal dielectric constant is strongly dependent on Cd-content and correlates with the normal electrical resistivity results. This correlation was discussed according to the grain boundaries scattering. [Copyright &y& Elsevier]

Abstract: A series of superconducting samples of type Tl0.8Hg0.2Ba2Ca2−x R x Cu3O9−δ, where R=Sm and Yb with , were prepared in a sealed quartz tube via a solid-state reaction technique. The electrical resistivity was measured as a function of temperature using the conventional dc four-probe technique. The fluctuation conductivity , above the superconducting transition temperature , was analyzed as a function of temperature using the Aslamazov and Larkin model. It exhibits five different fluctuation regions namely critical (cr), three-dimensional (3D), two-dimensional (2D), one-dimensional (1D) and short-wave (sw). The zero-temperature coherence length, the effective layer thickness of the two dimensional system, the wire cross-sectional area for one dimensional systems and the inter-layer coupling strength were estimated as a function of the substitution-content . Furthermore, the thermodynamics critical field, lower critical magnetic field, upper critical magnetic field, critical current density and Fermi energy are calculated from the Ginzburg number. [Copyright &y& Elsevier]

Abstract: The normal-state Hall effect for Tl0.8Hg0.2Ba2Ca2−x R x Cu3O9−δ, where R=Sm and Yb with , is measured above the superconducting transition temperature. The Hall coefficients , for all prepared samples, are positive and follow the Curie–Weiss temperature dependence type. Carrier-concentrations decrease as the substitution-content increases, as a result of the hole-filling mechanism. The sample with lower resistivity exhibits higher carrier-concentration. The Hall angle cot increases as the temperature increases and well fitted to the formula cot . The constant is found to be strongly dependent on the substitution-content and it is correlated to the residual resistivity . Finally, the variation of Hall mobility with both temperature and substitution-content is reported. [Copyright &y& Elsevier]

Superconductor of type Tl1 − xInxBa2(Ca0.9Y0.1)2Cu3O9 − δ for x = 0, 0.1, 0.2, 0.3 and 0.5 were synthesized using stoichiometric amount of Ba2(Ca0.9Y0.1)2Cu3O7 + δ precursor, Tl2O3 and In2O3 in a tube furnace at 870°C. The samples were characterized using the x-ray powder diffraction and the scanning electron microscope (SEM) whereas the composition of these samples were determined by micro-probe analysis. The transition temperature Tc for as-synthesized (Tl, In)-1223 compound, determined from the electrical resistance measurements, varied from 122 K for x = 0 to 100 for x = 0.6 These results indicate that the addition of indium decrease the transition temperature of Tl-1223 phase. This is because the addition of indium changes the Tl-1223 phase to the over-doped region. The argon annealing for some of these samples were studied. The effect of external applied magnetic field on the stage of transition is reported. Our data show that the transition width is increased by the increasing of the external applied magnetic field. The samples are more affected by the magnetic field with increasing of indium content. [ABSTRACT FROM AUTHOR]

Solid-state reaction technique was used to prepare superconductor samples with nominal composition of (SnO2)x(Bi,Pb)-2223 and (NiO)x(Bi,Pb)-2223, where 0.0 ≤ x ≤ 0.2 wt%. The prepared samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The impact of SnO2 and NiO nanoparticles addition on the thermopower of (Bi,Pb)-2223 was measured using a standard differential technique. The Seebeck coefficient values in the presence of NiO nanoparticles were about 5–37.9% higher than those obtained with the addition of SnO2 nanoparticles. Higher values of Seebeck coefficients result in a wide variety of applications of these superconductors such as electronics and thermoelectric devices. The obtained results were analyzed according to the two-band model (Fermi-liquid model) and the two-band model with an extra linear term. The Fermi velocity (υF), Fermi energy, Fermi temperature (TF), Fermi wavenumber (KF), Fermi wavelength (λF) as well as the carrier concentration (N/V) values were calculated and discussed as a function of the nanoparticles content. [ABSTRACT FROM AUTHOR]

A correction to the article "Stoichiometry Analysis and Normal-State Properties of SmBa2Cu3-x RuxO7-8 Superconducting Phase" by M. ME. Barakat, R. Awad and M. Roumie published online on December 21, 2015 is presented.

The influence of single wall carbon nanotubes SWCNTs and multi wall carbon nanotubes MWCNTs on Vickers microhardness of Gd-123 superconducting phase is studied. Samples of type (SWCNTs) x and (MWCNTs) x GdBa 2 Cu 3 O 7−δ , composite where, 0.0 ≤ x ≤ 0.1 wt.%, are prepared by solid-state reaction technique. The samples are characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM). Moreover the samples are examined by measuring electrical resistivity and Vickers microhardness. The obtained results showed an enhancement in the phase formation and grains connectivity up to 0.06 and 0.08 wt.% for SWCNTs and MWCNTs added samples, respectively. Likewise the superconducting transition temperature T c was improved at a low content of CNTs but it suppressed for higher concentrations. In addition, the analysis of Vickers microhardness measurements suggests that the most suitable model that describes the behavior of our sample is proportional specimen resistance PSR model. [ABSTRACT FROM AUTHOR]

Superconducting samples of SmBa 2 Cu 3 O 7− δ (Sm-123) added with various amounts of nanosized MnFe 2 O 4 addition (0.0−0.20 wt%) were investigated. The investigated samples prepared by the solid-state reaction method. The phase formation and microstructure of these samples were examined using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), proton induced X-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS). XRD data indicate that the volume fraction of Sm-123 increases as nanosized MnFe 2 O 4 increases up to 0.02 wt%. The elemental distribution and oxygen content were deduced from PIXE and RBS. The oxygen content slightly decreases as MnFe 2 O 4 wt% increases. The superconducting transition temperature ( T c ) and critical current density ( J c ) of the prepared samples were estimated from electrical resistivity and transport critical current density measurements. It was found that T c decreases as nanosized MnFe 2 O 4 addition increases, while J c enhances up to 0.02 wt%. Moreover, the temperature dependence of normal state electrical resistivity was studied in view of the pseudogap opening in order to determine the pseudogap temperature T * as a function of nanosized MnFe 2 O 4 addition. T * increases as nanosized MnFe 2 O 4 increased, indicating the enhancement of the pseudogap formation in HTSCs by adding magnetic impurities. The crossover to fluctuation conductivity near the T c is discussed. [ABSTRACT FROM AUTHOR]

Abstract: In this work, superconducting samples of type (Cu0.5Tl0.5)-1223 added by nano-SnO2 (0.0–1.0wt.%) were prepared by solid-state reaction technique. The prepared samples were characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS) for phase analysis and microstructure examination, respectively. Room temperature microhardness measurements were carried out at different applied loads (0.49–2.94N) for studying the performance of the mechanical properties of the studied samples. Furthermore, the experimental results of microhardness measurements were analyzed using different models in order to show the effect of nano-SnO2 addition on microhardness and elastic modulus. [Copyright &y& Elsevier]